Automatic combined coder and timed release telephone system



June 27, 1950 w. T. POWELL 2,513,049

AUTOMATIC COMBINED CODER AND TIMED RELEASE TELEPHONE SYSTEM Filed Sept.1'7, 1946 5 Sheets-Sheet 1 SLOW IOPFRHTE I 2.9

I N VEN TOR. W//VF/P0 I POWEL L K/i'xaLM HTTO/PA EY June 27, 1950 w. "r.POWELL AUTOMATIC COMBINED CODER AND TIMED RELEASE TELEPHONE SYSTEM '5Sheets-Sheet 2 Filed Sept. 17, 1946 INVENTOR. W/NFRED 7. POW'LL J zw w.'r. POWELL AUTOMATIC COMBINED CODER AND TIMED June 27, 1950 RELEASETELEPHONE SYSTEM 5 Sheets-Sheet 3 Filed Sept. 17, 1946 HTTO/P/VEY June27, 1950 W. T. POWELL AUTOMATIC QOMBINED CODER AND TIMED RELEASETELEPHONE SYSTEM Filed Sept. 17, 1946 5 Sheets-Sheet 4 INVENTOR.W/A/F/PFD 7. POWfLL J7 HTTO/P/VEY Patented June 27, 1950 AUTOMATICCOMBINED CODER AND TIMED RELEASE TELEPHONE SYSTEM Winfred '1. Powell,Rochester, N. Y., assignor to Stromberg-Carlson Company, a corporationof New York Application September 17, 1946, Serial No. 697,430

8 Claims.

This invention relates in general to automatic telephone systems, but itmore particularly pertains to small systems suited for installation intowns or villages. An automatic telephone system of this type isgenerally known as a C. A. X. and may have a capacity of ten lines, forexample. Usually the lines are party lines having either bridged orgrounded ringing circuits over which subscribers are signalled by meansof code ringing. Provision is also usually made for trunking calls toand from distant exchanges.

The main. object of the present invention is the provision of a combinedcommon relay type code interrupter and a relay type time release circuitfor use in controlling the connector link circuits, which may preferablyalso be of the all relay type.

Other objects and advantages of the present invention will be set forthin the specification and claims and shown in the drawings. Thecharacteristic features will be explained more in detail in thefollowing description of one embodiment of the invention, while variousother features and advantages of the system comprising this inventionwill be in part pointed out and in part apparent as the descriptionprogresses. For the purpose of simplifying the drawings and facilitatingthe explanation, various parts and circuits have been diagrammaticallyshown and certain conventional illustrations have been employed. Thedrawings have been made more with the purpose of making it easy tounderstand the principles and mode of operation, than with the idea ofillustrating the specific construction and arrangement of parts andcircuits that would be employed in practice. Thus the various relays andtheir contacts are illustrated in a conventional manner, the use ofsymbols being employed to indicate the connections to the terminals ofbatteries, or other sources of current, instead of showing all the wireconnections to these terminals.

The symbol indicates the negative terminal of the battery or othersuitable source of current, while the positive terminal of this samesource is illustrated by the usual ground symbol.

In describing the invention in detail, reference will be made to theaccompanying drawings which illustrate in a diagrammatic manner theapparatus and circuits employed. Those parts having similar features andfunctions are designated in the different figures by similar referencecharacters.

The complete line circuit, line finder circuit and allotter circuit havebeen omitted from the present showing since they form no part of thepresent invention. It will be obvious that any of the well knowncircuits of this type may be used, one preferred arrangement of the allrelay type being shown in Powell Patent 2,325,877, issued August 3,1943.

Referring to the drawings, Figure 1 illustrates in diagrammatic mannerthe usual arrangement by means of which a calling subscriber A isconnected to an idle link circuit by way of an associated line finder L.F., after which the connection is extended in response to dialedimpulses by way of the line connector, associated with the chosen link,to called subscriber B. As indicated in Figure 1, a common relay typecoder and time release circuit is associated with the link circuit inuse when the functions of this coder and time release circuit arerequired in connection with the call in progress.

The remaining figures are arranged with Figs. 2, 3, and 4 in this orderfrom left to right, with Fig. 5 directly below Fig. 2, and Fig. 6directly below Fig. 3. By placing the figures in this order and withcorrespondingly numbered lines in alignment the tracing of the detailedcircuits will be facilitated.

Since the present invention is concerned with the connector portion of alink in a relay type automatic telephone system, one such connector isillustrated complete in Figs. 2, 3 and 4. Furthermore, since the presentinvention is concerned with the common code ringing and the commonpermanent signal and conversation time release apparatus and circuitsfor cooperating with any of the connector links, such as the oneillustrated in Figs. 2, 3 and 4 to provide code ringing of the calledstations and the automatic release of permanent signal and conversationtimed connections, the complete relay type coder and timer isillustrated in Figs. 5 and 6. Relays A, B and C of Fig. 5 comprise apulse generator for supplying pulses for stepping the counting relaysXCl-XCI B through cycles to provide time out pulses for the time releaseof a connector under various conditions and to provide pulses foroperating common channel relays lCI-I|CH in proper combinations forproviding coded pulses for code ringing called lines by variablyoperating a connector ringing relay RR, all in a manner which will beexplained in detail.

In describing the operation of this invention in detail, it will beassumed that the calling subscriber A is connected to the link circuitof Fig. 2, in response to the removal of the receiver, in the mannerpointed out in the above mentioned Powell patent. Tip, ring and sleeveconductors ductors effects the operation of calling bridge 7 relay CBwhich closes an obvious circuit for operating slow acting relays-A.-Relay SA closes an obvious circuit for operating slowacting ree peaterrelay SAP. Relay ,S AP closes acircuit through its inner lower makecontact and; middle upper back contact of relay RBT, for operatingreverting call relay RC. The operation of relay SAP also closes acircuit 'from ground, make contact of this relay, break contact of relayCRL,.

conductor I6, break contacts in series of relays C5, C4, C3, C2, and CIto the winding of relay CX for operating this latter-relay. Relay CXconnects dial tone to the calling line as an indication that dialing maybegin.

The calling p-artynow dials the first or hundreds digit which, forexample, may be number 2, resulting inrelay- CB being releasedtwiceafterwhich it remains'operated. Thefirst release of relay CB closes a circuitfor operating counting relay Cl which extends from ground, breakcontactof relay CB, make contact of relay SA, conductor- I-l,break'contact of relay TT, conductor 1 8, break contact of relay BY;conductor 19, break contact of relay RI, make contact of relay CX andwinding to relay CI to negative battery. A circuit is also closed'atthis time for operating changeover relay CHO which may be traced fromthe above mentioned break contact of relay RLconductor 2i) and windingof relay 01-10 to negative battery. To prevent the release of relay CHOwhen relay RI is operated during impulsing (as will be later explained),the make contact of relay CHO bridges conductors l9 and 253 forproviding a substitute holding circuit-for this relay.

When relay CE is energized at the end of the first impulse, rela CX isreleased because its operating circuit is opened at a break contact ofrelay CI. Referring back to the release of relay CB at the beginningofthis first impulse, relay CX is locked in its operated position by wayof a circuit extending from ground; make contact of relay SAP, breakcontact ofrelay CB, conductor 26,- make contact and winding of relay CXto negative battery. With-relay CX released, as above mentioned, thedial tone is disconnected from the calling line and since relay ITF willbe operated before relay CX is next operated, this dial tone circuit is-m'aintained disconnected throughout the remainder of the connection.

In response to the remaining impulse of the first digit, relay CB-is'released, with the release operation of this relay extending groundby way of; conductor 26, through' a make contact of relay CI for lockingthis relay-operated, while the circuit from ground on "conductors 11, I8and I9 is extended through break contact of relay GK and make contact ofrelay CI to the winding of counting relay'CZ foroperating this relay.The lower innermakecontact of relay C2 ,closes a locking circuit forthis relay to conductor I6 and the lower inner break contact of relay C2opens thelocking circuit including this conductor which was extended torelay CI. Relay Cl does not release at this time, however, because of thI above described locking circuit.

It is believed that the above explanation of the control of the countingrelays by the transmitted impulses is sufiicient to indicate how theserelays are progressively operated, with the counting relay numbered incorrespondence with the number of the impulses in the transmitted digitbeing left operated at the. end 'of the series of impulses. Furthermore,it will be observed that .relay CEO is operated at the beginning of theseries of impulses and is released at the terminationtof the seriesbecause ground is removed from'conductors I1, [8, l9 and by relay CBremainingenergized long enough to permit relay CHO. to be released.

In thisparticular system it will be assumed that #3 is dialed for thefirst digit to-select 1 an interofiice trunk, or the like, when thisparticular system operates in connection with interofiice trunking,however, since such trunk servicecircuits form no part of the presentinvention they will be omitted from this explanation. The referencecharacters associated with the make contact of counting relay C3indicates a connection to the hundreds connector relay I-IC3, if andwhen provided.

Assumingthat this is aJfour-digit system, the first coderinging groupwill be selectedby digit i and the second code ringing group will beselected by digit 5. This is accomplished by the provision of two relaysH04. and I-IC5 which respond to the. above .mentioned first digitsrespec tively. Tens connecting relays TCI and TCZ of Fig. 4 areselectively responsive to the second digit (#l or #2.) since it isassumed that there are two tens groups offivelines each selected by theline connector. The third digit l, 2, 3, 4 or 5) selectivel operates anyone of the units connecting relays UCI to U05 inclusive, with theparticular line of eachpair selected by the units connector relay beingindividually selected by the particular tens connecting relay operatedby the tens digit; The fourth digit selects any one of ten code ringingcircuits, with the ten common code conductors being shown leading fromthe bottom of Fig. 3'. Lines 9 and H! are omitted from Fig. 6 'in'orderto simplifythe drawings. It will be clearly understood irom the"description which follows how conductor i-l'could be grounded by'relays302i and 30H to provide two short rings and how conductor ll! could begrounded by relays lCH;'-3'CI-I"and 50H to provide three short rings. 7

It will now be assumed that the first digit dialed is #4. This meansthat counting relay 06' will be in its operated position and the othercounting relays of the group will'be in their released positions whenrelay CHQ is released at the end of the first digit." A' circuit is nowclosed for operating hundreds connector relay HCG which extends fromground, make 'contact of relay SAP, break contact of relayCI-IO, breakcontact of first transfer relay ITF, conductor 27,

make contact of countin relay C4 and Winding leased at the end of thisseries of impulses.

T02 if the tens digit is #2.

eratedwhen the first digit is #5) and winding of relay H05 to negativebattery.

The operation of relay H04 extends the grounded stick conductor STK toconductor 29,

counting release relay CRL for operating this relay. Relay CRL closes a.circuit for operating relay ITF which extends from grounded conductor29, ,make contact of relay CRL and winding of relay ITF to negativebattery. Relay ITF closes a locking circuit for itself by bridging theabove mentioned make contact of relay CRL, at the same time that itopens the above described operating circuit for relay CRL, which efiectsthe release of this latter relay.

'During the time that relay CRL is operated, the ground connection onconductor I6 is opened at a break contact of relay CRL for effecting therelease of the counting relay left operated. When relay CRL releases,the above circuit for operating relay CX is again closed to groundedconductor Hi.

The tens digit is next transmitted and in response to the impulses ofthis-digit the counting relays are again operated, with relay CHO beingoperated at the beginning of the series and re- At the termination ofthe tens series of impulses and the consequent release of relay CHO acircuit is closed for operating the selected tens connector relay TC! ifthe tens digit is #l and The particular TC relay which is operated islocked in its operated position by means of a *cincuit extending fromground on conductor STK and the make contact of the particular selectedTC relay. At the same time, this grounded conductor STK is extended backby way of conductor 30 and break contact of the second transfer relayZTF to the winding of relay CRL for operating this relay. The operationof rela CRL extends grounded conductor 30 by Way of a make contact ofrelay I'I'F and a make contact of relay CRL to the winding of relay 2T5for operating this relay, which in turn completes a locking circuit foritself at its make before break contact to grounded conductor 343 at thesame time that it opens up and releases relay CRL.

The operation of relay CRL again opens up conductor it for eifecting therelease of the counting relay left operated and when rela CRL isreleased, relay CX is again operated to prepare the counting relaycircuit for the units digit.

In response to the series of impulses making up the units digit, relayGB is again intermittently released for sequentially operating thecounting relay chain and when relay CB remains operated at thetermination of this series of impulses the sounding relay correspondingto the number of impulses in this digit is left operated. Relay CEO isagain operated and released, the release it in its operated position andextends conductor 1 STK back by way of conductor 3| and break contact ofthe #3 transfer relay STF to relay CRL for again operating this relay.The operation of relay CRL extends grounded conductor 3i through a makecontact of relay 2TB and a make contact of relay CRL to the winding ofrelay 3TB, which operates and locks this relay at its make before breakspring combination-and opens up and releases relay CRL for againreleasing the counting relay left operated, after which relay CRLreleases for again operating relay CX to prepare the counting relaycircuit for the last or station digit.

It is not believed necessary to explain the operation of the circuitwhen a busy line is selected, since this feature forms no part of thepresent invention and since it has been pointed out in detail in theabove mentioned Powell patent. It will be assumed that the called lineis idle when relay 3TF is operated after the units digit is received. Itwill further be assumed that line #I I connecting to substation B ofFig. 4 is selected, which means that relay UCI is operated incombination with tens relay TCI. It will be obvious from the linenumbers associated with the UC relays of Fig. 4 how the five lineshaving tens digit #1 are selected by relay 'I'CI in combination with anyone of the UC relays and how the other five lines having tens digit #2are selected by means of the same UC relays in combination with relayT02.

With relays TC! and UCI operated in response to the transmission of thetens and units digit and the operation of relay 3TF, sleeve conductor Sof line #H is extended through make contact of relay UCI, make contactof relay TCI, conductor 32, make contact of relay 3TB, break contact ofrelay BY and make contact of relay SAP to ground. This ground applied tosleeve conductor S of the called line makes this line busy to othercalls and operates the usual cut off relay of the called line.

It will first be assumed that relay H04 was operated in response to thehundreds digit when the line having tens digit I and units digit I isselected. This means that code ringing common conductor I is connectedto ringing conductor 33 for operating ringing relay RR over a circuitwhich will be later described. If relay H05 is operated in response tothe first digit, in combination with counting relay CI for the stationdigit, then ringing conductor 33 will be extended to common codeconductor 6. It will thus be obvious that relay H04, operated when thehundreds digit is #4, extends the ringing circuit of the link to commoncode ringing conductors I to 5, inclusive and that relay H05, operatedwhen the first digit is #5, extends the link ringing conductor 33 tocommon code conductors 6 to Hi, inclusive, these common code conductorsbeing selectively extended to the contacts of the HC relay by thecounting relay left operated by the station digit.

When the station digit is dialed, relay CB functions to operate thecounting rela chain in the previously described manner, with relay CHObeing operated at the beginning of this digit and released at the end ofthe digit. The operation of relay CHO closes a circuit for operatingringing relay RI which extends from ground, make contact of relay SAP,make contact of relay CI-IO, make contact of relay 3TB, conductor 34,break contact and winding of relay RI and resistance to negativebattery. Relay RI extends the grounded conductor STK to its winding bymeans of its make before break contact for locking this relay in itsoperated position. It will be noted that relay R1 is operated at thebeginning of the station digit impulses. At the end of the stationseries of impulses the release of relay CHO closes a circuit foroperating test relay TT which extends from ground, make contact of relaySAP,

break: contact of relay CHO, ma=kef contacts in series: ofrelays I'I'F,2TF and 3TF,- conductor 35, make contactof'relay RI, conductor, breakcontact of relay BY, conductor 31 and upper winding of relay TT tonegative battery. Relay TT closes a bridge point across the abovementioned make contact of relay RI, which is effective to lock relay ITin its energized position.

When pick-up conductor PU is grounded at the beginning of the coderinging cycle, as will be later explained, this grounded pulse isextended through make contacts of relays RI and TT to the upper Windingof relay CI for operating this relay. Relay CI locks itself operated tothe grounded hold conductor HLD, this conductorbeing maintained in itsgrounded condition until the completion of this code ringing cycle, thusholding relayCI. in its operatedposition by way of its lower winding.

' With relay CIv operated, ringing conductor 33 is extended to ringingrelay RR so that this relay isintermittently operated in accordancewiththe selected code for applying ringing generator to the selected calledline in accordance with this code. This generator circuit extendsthrough make contacts of relay RR, conductors 38 and 39, make contactsof relay TI, conductors 4i) and ll, make contacts of relay TCI, makecontacts of relay UCI and the called subscribers line for ringing thebell of the stations on this line in accordance with the selected code.Small condenser 42 bridged across the upper break contact of relay RRpermits a, small portion of the ringing current to flow back over thecalling line to give the calling party an indication that the calledstation is being rung.

When the called party answers, the called line circuit, extended by wayof break contacts of relay RRto the windings of relay AB effects theoperation of relays A13 for short-circuiting and releasing relay RI andterminating the ringing signal. It will benoted that relay CI must be inits released position, thus indicating the interval between the codecycles, before relay ABv can effect the release of relay RI. This isbecause the contact l3. of relay .AB cannot be effective if relay CI isoperated because its contact #44 will then be open.

Conversation is carried on in the usual way and the release of theconnection is efiected by the calling party hanging up and releasingrelay CB which-efiects the release of relays SA, SAP and RC. It will beunderstood that relays RC and RBT perform no functions in connectionwith a call of this type, these relays being-of use only in connectionwith a reverting call, which forms no part of the present invention andwhich is fully explained in connection with the above men' tioned Powellpatent. e

The release of relays SA and SAP effect the release of all other relaysused in connection with this call by opening up the connection to groundwhich is used to hold these relays in their operated positions.Consequently, the counting relays will be released, the particular HC'relay which was operated will be released, the TC and UC relays will bereleased, the TF relay will be released, the TT relay will be released,the AB relay will be released and the called line circuit will berestored to normal.

Referring to Figures 5 and 6, it will now be explained how the series ofcounting relays XCI to XCIB, inclusive, are operated by the impulsegenerating relays A, B and C for providing the various code ringingcombinations, as well as for providing the-time-relase feature.

With the systenr at-rrest,--relay -,A normally energized over acircuit:extending through a break'contact of relay C. When relay CI'ofany link circuit is operated inresponse to a call, as previouslydescribed; the ground applied'to start conductor STT closes a circuitbyway of the lower winding of start relay ST of Fig. 6 for operatingthis relay. Relay ST closes a circuit by way of conductor for operatingrelay B, Which'in turn closesan obvious circuit for operating relay C.With relays C and ST- energized, :relay A is released for effectingthe-release of relay B, which in turn'opens upand releases relay .C.With relay C released, relay A is again energized, closing the abovedescribed circuit for again operating. relay-B,-which--in turn effectsthe -operation of relay C. This cycle of operations, relaysA, B and Cbeing released in sequence, followedby the operation of these relays insequence, is repeated as long. as the ST relay remains operated. Thiscycling of the A, Band C relays provides thetime generated impulses forcontrolling the operation of the counting relay chain, comprising relaysXCI to X015, inclusive. It will be assumed that the release time of eachof these impulsegenerating relays is approximately one third of a,second. This means that they will go through a complete cycle ofoperations in approximately one second, thus providing a series of onesecond cycles for controllingthe countingrelay chain.

Relay CXI is energized by the operation of relay ST over a circuitextending from ground,

make contact of relay ST, conductor 46, make contact 41 of. relay A,break contact of relay X02 and winding ofrelay XCI to negative battery.Relay XCI, in operating, closes a first locking circuit for itself whichextends. from grounded conductor d6, make contact of relay" XCl and theabove mentioned break contact of relay XCZ tact of relay XCl', breakcontact 43 of relay A,

and winding of relay XCZ to negative battery. The operation. of relayXCZ opens up the first locking circuit of relayv XCl, but this relayisnot released at this time because of the above described second lockingcircuit for this relay. The operation of relay X02 closes a firstlocking circuit'for itself extending from grounded conductor 46, makecontact of relay XCI and make contact of relay XCZ to the winding ofthis latter relay.

When relay A is next operated, the second locking circuit of relay XC Iis opened for effecting the release of this relay which in turn opens upthe first locking circuit of relay XCZ, but this latter relay does notrelease at this time because the operation of relay A closes a secondlocking circuit for relay XCZ'before its first locking circuit is openedby the release of relay XCl. This second locking circuit for relay XCZextends from grounded conductor 4%, make contact 4'! of relay A, makecontact and winding of relay XCi Z to negative battery. When relayA-next releases this second locking circuit for relay XCZ is opened forefiecting the release of this relay. When relay A is next operated,relay XC'I is again operated and locked and when relay A is nextreleased-relay XG'I- is further locked-,- relay X02 is operated andlooked, all in the manner previously described. When relay A is nextoperated relay XCI is released and when relay A is next released, relayX02 is released all in the same manner as previously described.

It will thus be seen that counting relays XCI and X02 go throughcomplete operating and release cycles in approximately two seconds, Withrelay XCI being operated the first time when the common coder is seizedand thereafter operated on alternate operations of relay A. Relay XCI isreleased on the other alternate operations of relay A. Furthermore,relay X02 is operated at each alternate release operation of relay A andis released at each other alternate re-.

lease operation of relay A.

Contacts 51 and 58 of relay X02 control the operations and releases ofrelays X03 and X 3 in exactly the same manner that contacts 41 and E8control the operations and releases of relays XCI and X02. Contacts 61and 68 of relay X04 control the cycling of relays X05 and X05 in exactlythe same manner that contacts 51 and 58 control the cycling of relaysX03 and X05. Contacts H and 78 of relay X06 control the cyclingof relaysX07 and X08 in exactly the same manner that contacts 61 and 68 controlthe cycling of relays X05 and X06. Contacts Bl and 88 of relay X08control the cycling of relays- X09 and X010 in exactly the same mannerthat contacts l1 and i8 control the cycling of relays X07 and X08.Contacts 91 and 93 of relay XClfl control the cycling of relays XCH andX012 in exactly the same manner that contacts 81 and 88 control thecycling of relays X09 and X010. Contacts I01 and 08 of relay X0l2control the cycling of relays X0l3 and XCM in exactly the same mannerthat contacts 9! and 98 of relay XCH] control the cycling of relays X0!l and X0l2. Contacts Ill and H8 of relay X014 control the cycling ofrelays X0|5 and XOI6 in exactly the same manner that contacts I01 andH38 control the cycling of relays X0l3 and X014. Contacts l2! and I28are not used in the present disclosure, but are illustrated to indicatehow additional counting relay pairs may be controlled if and whendesired.

Since relays X01 and X02 complete a cycle of operations for every twocycles of the impulse generating relay A and since relays X03 and X04 gothrough a complete cycle of operations for every two cycles of relaysXCI and X02, it will be seen that the number of channel circuits (two)which may be selected by the first group of counting relays X0! and X02is doubled (providing four) by the provision of the second group ofcounting relays X03 and X04.

Furthermore, since relays X05 and X06 go through a cycle of operationsfor every two cycles or relays X03 and X04 (four cycles of relays XCIand X02), the number of channels is equal to eight or double the numberof counting relay pairs. Consequently, for each pair of counting relaysadded to the group the number of channel circuits which may be selectedis doubled. In other words, this arrangement provides a combination ofselected circuits or channels which is equal to two raised to the powerof the number of groups of counting relays, that is the number ofcircuits or channels selected by the counting relay chain increases ingeometrical progression.

From the above discussion of this circuit arrangement, it will be seenthat it takes approximately 2 seconds for relays XCI and X02 to completea cycle of operations. It takes approximately 4 seconds for relays X03and X04 to complete a cycle of operations. It takes approximately 8seconds for relays X05 and X05 to complete a cycle of operations. Ittakes approximately 16 seconds for relays X01 and X08 to completev acycle of operations. It takes approximately 32 seconds for relays X09and XClll to complete a cycle of operations. It takes approximately 64seconds for relays X0l l and X0l2 to complete a cycle of operations. Ittakes ap-- proximately 128 seconds for relays X0l3 and X0114 to completea cycle of operations. It takes approximatel 256 seconds for relays X015and XCHS to complete a cycle of operations. This provides a cycle ofapproximately 4 minutes and 16 seconds, with means for controllingchannel circuits at any one of the combinations of one second cycles forproviding code ringing and time release timing functions.

In'describing the code ringing and the time release functions of thecommon coder circuit, it will be convenient to refer to the operationsof relay A as being divided into a series of on and ofi positions. Theon positions are those during which relay A is operated and the ofipositions are those during which relay A is released. From the aboveexplanation, it will be noted that the position of relay XCI is shiftedat the beginning of each on of relay A, relay XCI being operated at thebeginning of each odd on and released at the beginning of each even on.Furthermore, relay X02 is operated at the beginning of each odd offperiod and is released at the beginning of each even off period.

Continuing with the operation of the counting relay chain, channel relayICH is energized during the second on period over a circuit extendingfrom ground, break contact of relay X08, break contact of relay XCI,make contact of relay X03, break contact of relay X01, conductor 49 andwinding of relay ICH to negative battery. Relay ICH closes a lockingcircuit for itself extending from ground, make contact of relay ST,break contacts of relays ICE to 20H inclusive and make contact of relayICH to the winding of relay ICH. It will be pointed out at the time thateach-channel relay (except the last), when operated, is looked over thecircuit to ground at the make contact of relay ST until the nextsucceeding channel relay is operated, thus providing an overlap so thata code conductor leading to the connector link will not be interruptedwhen this code conductor is to be maintainedvenergized by a succeedingchannel relay.

Returning to the operation of the channel relays, relay 20H is operatedduring the third on period over a circuit extending'from ground, breakcontact of relay X08, make contact of relay XCI, make contact of relayX05, break contact of relay X01 and conductor 55 to the Winding of relay20H.- The operation of relay 20H closes a locking circuit for itself andopens up the locking circuit for relay ICH, which is released at thistime.

Relay 30H is operated during the fourth on period over a circuitextending from ground, break contact of relay X08, break contact ofrelayXCl, break contact of relay X03, make contact of relay X05,conductor 50' and winding of relay 30H to negative battery. Theoperation of relay 30H closes a locking circuit for itself and opens thelocking circuit for relay 201-1 foreffecting the-releasetof'this latterrelay.

Relay 40H is operated during the fifth on Relay -'ICH'-is operatedduring ECH' to negative-battery. Relay 50H closes -a locking circuitfor*itself"andopens the locking circuit for-relay- 46H for effecting therelease of this latter relay.

' Relay BGHisoperatedduring the seventh on period over a circuitextending from "ground. break "contact of relay-xeil make contact ofrelay -XC I; breakcontact of relay XC-,-'mak'e contact of "relay XC'I,conductor'53 and-winding of relay 6CH-to-negative battery. *RelayBCI-Icloses a locking :circuit for itself and-opens the'lock-ing circuit--of--relay 501-1 for effecting the release ofthis-latter relay. I

the eighth on period over a circuit extending from ground, break contactofrelayXCB,breakcontact of relay XC I break contact of relay XC3',-breakcontact of 1 relay X65, =make contact '0f--relay-XC-'|,-'conductor-54 andwinding of-relay 'ICH-tonegative battery. Relay 'ICI-Icloses-a locking circuit for itself which extends through abreak-contact ofrelay XCI and opens up the locking circuit for fiGl-lforefiectingthe release ofthis-latter-relay.

When relay "XC l is-energizedduring: the ninth on-period, the abovedescribed lockingcircuit forrelay-ICH is opened-foreifecting the releaseof this latter relay.

It will thus'beseen that channel relays'JGI-I to lCI-I;inclusive,aresequentially operated and" released; with I each of these-relays' being-operated during succeeding -on' periodsof the A relay 1cycles. Since the cycles of-the A relaycompr-iseapproximatelyone--second--and -since there are sevenchann'elrelays inthesystem,-an: approximately 7 second ringing cycle is provided.-"Fellowing this 7 second ringing cycle, the impulse generating relaysand the counting e relays continue operating inthe abovedescribed mannerfor another approximate-'7 seeond'intervaLbut during this portion of therelay operation-,thechannel relays are not operated because -relay-XC8-- is 1 operated during the eighth os- -period- (after 1 relay lCI-Ihas beenoperated) for openingup' the above traced connection toground'which operates these channel relays. During' the 16th off period,- relayXCB is released and, since the impulse generating relays and thecounting relays continue operating with relay X08 in its normalposition, another ringing cycle is efiective for operating-the channelrelays in the manner previously described. -'It will-be understood thatduring the complete 4 minute and -16-second (approximate) cycleabovementioned the circuits I forcontrolling the channel relays arerepeatedlyeflective since-counting relays'XCl and X08, elusive, which controlthese channel relay circuitsrepeat their cycles in the above described 3order. The counting relays'XCQand X016, (in combination with relays -XC|to XCB inclusive) are used to provide the timing for the time releaseportion of the circuit, as will be later explained.

Referring to the contacts on channel relays IGH 12 to 'l'GI-I,inclusive, it will be observedthat,when a connector li-nkselects codeconductor I ,-:-one long ring -will-be provided-because cenductor-# Iisenergized during the-time that-relays IGH;2GI-I and 3GP. are intheiroperated positions.- Gode con ductor #2 provides one long and oneshort-ring, separated by a pausebeoa-use this code conductor isenergized byrelayslGH QGH ilCI-I and 50H. Code conductor#Sprovides-twolong rings with a pause between because-this conductoris-energizedwhen relays NIH.- ZCI-I, 30H; 5GB; SSH and lCI-I arein theiroperated positions. --W-hen code conductor #4 is selected, one long andtwo short ringsare providedbecause this conductor is energized bychannel relays IC'I-I, nZGH, 3CH,-5CI-I and 'ECH. When codeconductorisselected, two short and'onelong rings areprovidedbecause thisconductor is-energized by the operation ofrelays lCI-I, 3CI-I- and 501-1to lCH, inclusive.- When code conductor #fi'is selected the ringprovidedis one short, onelong-and-one shortbecause thisconductor is energized bythe I. 3, 4-, fraud 1 channel relays. When code-conductor #lis-selectedone short and one long rings are provided because this conductor isenergizedby the I, 3, it and ii-channelrelays. When code conductor #8-is-selected fourshort-rings are provided becausethis conductor isonlyenergized by the operations of the I, 3, 5 and 1 channel relays.

It will be "recalled that a CI relay of a connector link circuit may beenergized at thebeginning of a code cycle. This is becausepick-upconductor PUis connectedto' ground ata breakcontact'of relay X08, by wayof break contacts of relays XC'l, X05; X03 and X01. Consequently, whenrelay XCHs operated during the first on period, the pick-up'conductor'is disconnected from ground so that another connector link cannot startthe application of a'ringing code to a called line during a code cycle,thus preventing the application of a'f-alse or incomplete code to theline; Since the pick-up conductor is not again energized until the 16thon period with relays XC8','XCL XC3; XCE'and XC-l all in their releasedpositions and since this 16th on period is well after the coderinging-portion of the cycle,-it is proper to then energize the-pick-upconductor so that one or more connector links may operate their CIrelays.

As. above mentioned, an operated CI relay; is locked in its operatedposition to ground on hold conductor HLD. Since this conductor isgrounded at a'break contact of relay'XCdat any time the pick-upconductor is energized a locking circuit is provided for the CI relays;Furthermore, since this hold conductor is not de-energized until relayXC8 and relay XCd-are-both-energized at the same time, whichhappens-during the Nth-off period, it follows that anoperat'ed CI; relaywill be locked in itsoperatedposition'until'after theoode ringingportion ofthe cycle-is completed thus providing 'meansfor preventing theinterruption ofa code once started even though theconnection'isreleased. It will-also be obvious that any CI- relay which is lockedoperated provides a ground to conductor STT for holdingrelay ST operatedand that relay"XC8 provides a locking ground ior locking relaySToperatedby way-ofconductor fill, thusproviding means for maintaining thecounting and 1 channel relay circuits active until the end of a completeeo'decycle at which time (in the 16th ofiperiod) the --locking'circuitior relay ST isopened by the release of relayXCB.

The 'timerelease portion of the circuit-'will'now be explained. As abovementioned it takes ap- 13 proximately 256 seconds for the countingrelays" XCI to XCIB, inclusive, to go through one complete cycle ofoperations before a second cycle is started. Referring to the connectorlink circuit of Figure 2, it will be noted that the timer relay TM willbe operated by way of its lower winding if the call is unanswered whenpick-up interrupter common conductor PU2 is energized. The circuit fromthis common pick-up interrupter extends through a break contact of relayAB (deenergized because the call is unanswered), break contact of relayTM, make contact of relay SAP, break contact of relay AB and lowerwinding of relay TM to negative battery. Common pick-up conductor PU2 isenergized at the beginning of each 2 minute, 6 second (approximate)cycle by way of a circuit extending through make contacts of relays XCIand XCZ, break contacts of relays XC4, X05, X08, conductor 63, breakcontacts of relays XCIO, KC and XCM. This circuit through theseparticular relay contacts is only completed at the beginning of the 2minute, 6 second cycle and is maintained opened throughout the remainderof such cycle.

In other words, common pick-up interrupter- PU2 is energized atintervals of approximately 128 seconds. This provides a 2-4(approximate) minute permanent signal time release feature, since theoperation of a TM relay closes a locking circuit for itself and opens upthe above described energizing circuit at the time the relay operates.The operation of relayTM also removes direct ground from stick conductorSTK' (which holds the finder portion of the link in its operatedposition) and substitutes therefor a ground by way of a make contact ofrelay TM and a break contact of relay AB to hold conductor H2 which is:energized at any time conductor PU2 is energized and is maintainedenergizeduntil just a short interval before conductor PU2 is nextenergized. This is because conductor H2 will be energized as long as anyone of the counting relays XCL. X02, X03, XC5, XC'I, XCQ, XCI l or X013is ener-- gized. Recalling the geometrical progression of operations ofthese counting relays, it will be ob vious that some one of thesecounting relays is in; its operated position for applying ground tocon-, ductor H2 until the end of the 127th "off period,. at which timeconductor H2 is momentarily deenergized to permit the release of a linefinder by removing ground from conductor STK as above mentioned.Conductor H2 is again energized by the operation of relay XC'I beforeconductor PU2 is energized by the operation of both relays XCl and X02,thus providing sufificient time to release: out any desired connection.

It will be apparent that in the event of the closure of the circuit tothe lower winding of relay TM, just after conductor PU2 is momentarilyenergized, it will then be necessary for the circuit to measure offapproximately 2 minutes and 6 sec-- onds before conductor PU2 is againenergized for operating relay TM. Then it is necessary to measure offanother two minutes and 6 seconds (approximately) before conductor H2 isde-energized for releasing the connection. This means that under certainconditions it will be approximately 4 minutes and 12 seconds before thepermanent signal release feature is effective, while under otherconditions it will be efifective in approximately 2 minutes and 6seconds.

Pick-up conductor PU is not energized until approximately 256 secondsafter the start of. a'

cycle, since this conductor extends through con-, tacts on the samerelays as conductor PU2 and in addition it extends through a breakcontact ofrelay XCIE, which takes twice as long to complete its cycle asrelay XCM. Consequently, during the talking condition of the connectorlink, relay TM may be energized by way of its upper winding and makecontacts of relay AB and hold conductor H5 is momentarily de-energizedthe same as above described for conductor H2, except by the additionalmake contact of relay X015, which operates in a cycle twice as long asrelay XCI3. Therefore, the connection may be released while it is intalking condition by means. of the 4 minute, 16 second (minimum) or the8 minute, 32 second (maximum) cycle provided by the PU5 and H5 commonconductors. This type of connection may likewise require variable timesbetween the minimum and maximum above mentioned. 7

Relay TM is differentially connected so that it will be de-energized ifpick-up conductor PU5 is energized with the connector in its talkingcondition, if relay TM had been previously energized by pick-upconductor PU2. This is to render the control of relay TM dependent onthe pick-up and hold circuits determined by the talking or nontalkingcondition of the connector. Without this differential arrangement itwould require 'tWO separate relays for the two separate timingfunctions.

A disconnect tone is applied to a talking connection by way of makecontacts of relay AB and TM of the link circuit and by way of the commontone conductor, if relay TM has been maintained in its energizedposition for approximately 30 seconds less than the conversation timerelease period. This tone is, therefore, applied sufiiciently in advanceof the automatic release of a connection to give the talking partiesample warning. The common tone circuit extends through make contacts ofrelays X82, X03, XCt, XC8, conductor EM, make contact of relay XCH),break contact of relay XClZ and make contacts of relays XCl l and X0! 6to the tone source. By analyzing the time during the complete cycle atwhich these relay contacts are in their closed positions it will bedetermined that the tone is connected momentarily to the common toneconductor approximate- 1y 30 seconds before the release function iseffected.

1 Although no line nor line finder circuits have been shown in thepresent disclosure, it will be obvious to those skilled in this art thatit is only necessary to provide line circuits of the lock-out type, suchfor example as shown in the above mentioned Powell patent, to maintainsuch lines disconnected from all trunk or link circuits when they arereleased by the common time release circuit removing ground fromconductor STK.

Although one specific embodiment of the present invention has beenshown, it is to be understood that Various rearrangements of thecircuits may be made without departing from the spirit of the invention.

What I claim is: p

1. In a telephone system, an exchange, lines in said exchange, aplurality of trunk circuits common to said lines, means controlled overone of said lines for connecting it to and disconnecting it from any oneof said trunk circuits, a time release mechanism common to said trunkcircuits, a release relay associated with each of said trunk circuits,additional means including said release relay in its operated positionfor disconnecting said one line from a trunk circuit to which it hasbeen connected, meansv including said time release mechanism formeasuring off a distinctive time interyaLimeans', operative under the,control,

said exchange, a plurality of trunk circuits common to said lines, meanscontrolled 1 over one pf saidlines forconnecting ibitO and disconnectingit from any, one of said trunk circuits, atime release mechanism commonto said trunkjcircuits,

a release relay. associated with each of saidltrunk.

circuits, additional means including said release relay in its operatedposition for disconnecting said one line from a trunk circuit to whichit has been connected,means including said time release mechanism for:measuringv off two distinctive time intervals, means operative :underthe control of said mechanismlfo-rcausing said release relay to operateat the end of one of said time intervals, means operative under :thecontrol of said mechanismifor releasing said release relay whereby thedisconnection of said oneline from said,trunk* circuit by saidadditional means is prevented-and means operative under the control ofsaid mechanism for causing said relay to again operate at the end of theother Iofv said time intervals.

3.In combination; a pulse generating relay;

means. fOr operating said pulse generating relay through a plurality ofcycles; a plurality of counting relay group-s operative throughaplurality of steps, each group of which comprises a first and secondcounting relay; means for causing the first of said relay groups tocomplete only one operatin cycle in response to two of the operatingcycles of said pulse generating relay; means for'causing each of saidremaining relay groups to complete only one operating cycle inresponse-to two of the operating cycles ofpitsjpreceding relay group; aplurality of link circuits; a

pair of time control conductors common to said link circuits; meansincluding-said counting, relay groups for applying pairs of timedpulsesin combination'to said time control conductors; and

means controlled by said pairs of timed: pulses for efiecting therelease of said link circuits.

4; "In combination; a pulse: generating, relay;

means for operating said pulse, generating relay:

through a plurality of cycles; a plurality v,of counting relaygrcupsoperative through a plurality of steps, each groupof which comprises afirst and second counting relay; means'forcausing the first ofsaid relaygroups to complete only one operating cycle in iresponsepto two-of ztheoperating cycles of said pulse generating relay;

meansfor causing each of said remaining relay groups to complete onlyoneoperating cycle in response to two of the operating cyclesof itspreceding relay group; a plurality; of link circuits; a pair of timecontrol conductors common,

to said link circuits; means including said counting relay groups forapplying pairs 30f timed pulses in combination to .said time control.con-

ductors, said timed pulses having a ratio to; each other of more thantento one; andmeanscontrolled by said pairs of timed pulses for efiectingthe release of said link circuits.

'5.'In combinationya pulse generatingrelay;

means for operating said pul'se'generating -relay' through'a pluralityof cycles; a plurality of counting relay groups operative through aplur-l ality' cf steps, eacli group of which comprises a firstandasecondcounting relay; means for causingtthegfirstriof said. relaysgroupsto complete onlygone operating cycle in response to two of the:operating'cycles of saidpulse generatingrelay; :means forcausing each,of said remaining relay groups to complete only one operating cycle :inresponses-to two of the operating cycles of 'its'preceding relay group;a plurality of link circuits; a pair of time control conductors commontoisaidlink circuits; a plurality of coded channel conductors; and meansincluding said countingrelay groups for applying pairs oftimedlpulsesxin combination to said time control conductors and forapplying timed pulses to said. coded channel. conductors.

6. sIn .a telephone system, an exchange, lines terminating. in saidexchange, a connecting link, selectively'controlled means including afirst series of, countingrelays associated with said. link forestablishing a connection between a calling line and a called one ofsaid lines, a combined coder: and timesirelease mechanism including aplurality of pairs of counting. relays, :means for causing thefirstpair'ofcounting relays to 0perate ."through' a plurality: ofcycles, means for causingieach succeeding pair. of counting rela s tooperate through a cycle in response to two operating cycles: of thepreceding pair of counting relays; means including contacts on a portiononly ofsaid counting relay pairs for restoring said link to normal aftera predetermined time following the. seizure of the link, and'meansincluding contacts .on all of said counting relay pairsjfor restoring.said link to normal after a longer time than said predetermined timefollowing the seizure .of the link.

'7. ma telephone system, an exchange, party lines terminating in saidexchange, a connecting link, selectively controlled means including afirstseries of counting relays associated with said link forestablishing a connection between a calling-line. and 2, called one ofsaid party lines, a combinedcoder and time release mechanism including aplurality of pairs'of counting relays, means for causing the first pairof counting relays to operate through a plurality of cycles, means forcausing each succeeding pair of counting relays to operate through acycle in response to two operating cycles of the preceding pair ofcountingrelays, means including contacts on a portion only of saidcounting relay pairs forz'restor'ing said linkto normal after apredetermined time. interval is measured off following the seizure ofthe link; meansincluding contacts on all of said counting relay pairsfor restoring said link to normal after a time interval has beenmeasured off which is longer than said; predetermined time intervalfollowing the-seizure of the linkgand means including contactsonaaportion: only of said counting relay pairs for vapplying codering-ingsignals to said partyjlinesp f 8.3,.In "a telephone system, an exchange,party lines terminating insai'd exchange,- a connecting link,"selectively controlled means. including a first series of countingrelaysassociated with said link tfor establishing :a connection betweena calling line and 9,. called one of said party lines, a"combinedycoderand time release mechanism including a plurality of pairs'of countingrelays, meansior causing, the first pair of counting relays ,to operatethrough a plurality of cycles,.'1ne'ans for causing. each succeedingpair offcountlng relays to operate through a cycle in response to tw ooperatingcycles of the preceding pair of counting relays, meansincluding contacts on a portion only of said counting relay pairs forrestoring said link to normal after a predetermined time interval ismeasured ofi' following the seizure of the link, means includingcontacts on all of said counting rela pairs for restoring said link tonormal after a time interval has been measured off which is longer thansaid predetermined time interval following the seizure of the link,means including contacts on a portion only of said counting relay pairsfor applying code ringing signals to said party lines, and meansincluding contacts on a portion only 01 said counting relay pairs forapplying a, Warning signal to said connection prior to the restorationof said link to normal after said longer interval of time.

WINFRED T. POWELL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,513,049June 27, 1950 WINFRED T. POWELL It is hereby certified that errorappears in the specification of the above numbered patent requirmgcorrection as f0 owe: l

Column '5, line '60, for sounding read cownti/ng;

and that the said Letters Patent should be read as corrected above,sofithat the' same may conform to the record of the case in the PatentOfiice.

Signed and sealed this 21st day of August, A. Dr 1951 THOMAS F. MURPHY,r Asaz'atant Commissioner of

